Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 12 - Review - Exercises - Page 891: 75

Answer

32

Work Step by Step

$n!=n(n-1)(n-2)\cdot...\cdot 2\cdot 1$ $0!=1$ $\displaystyle \left(\begin{array}{l} n\\ r \end{array}\right)=\frac{n!}{r!(n-r)!}$ ------------------------- $\left(\begin{array}{l} 5\\ 0 \end{array}\right)+\left(\begin{array}{l} 5\\ 1 \end{array}\right)+\left(\begin{array}{l} 5\\ 2 \end{array}\right)+\left(\begin{array}{l} 5\\ 3 \end{array}\right)+\left(\begin{array}{l} 5\\ 4 \end{array}\right)+\left(\begin{array}{l} 5\\ 5 \end{array}\right)$ $=\displaystyle \frac{5!}{0!5!}+\frac{5!}{1!4!}+\frac{5!}{2!3!}+\frac{5!}{3!2!}+\frac{5!}{4!1!}+\frac{5!}{5!0!}$ $=1+5+10+10+5+1$ $=32$
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